Spring adjuster for overhead doors



March 26, 1957 RQBINSQN' 2,786,231

SPRING ADJUSTER FOR OVERHEAD DOORS Filed Oct. 6, 195.4 2 Sheets-Sheet 1DAV/D M ROBINSON MM W ATTORNEYS Sign- March 26, 1957 Filed Oct. 6, 1954D. M. ROBINSON SPRING ADJUSTER FOR OVERHEAD DOORS 2 Sheets-Sheet 2 DAV/D INVENTOR M ROB/IVSON TTORNEYS o -a a SPRING ADJUSTER FOR OVERHEADDOORS David Malcolm Robinson, New Britain, Conn, assignor to The StanleyWorks, New Britain, Conn a corporation of Connecticut AppiicationOctober 6, 1954, Serial No. 460,539

Claims. (Cl. 16-197} This invention relates to improvements in overheador roll-up doors of the type having torsion counterbalance springs, andmore particularly to an improved spring adjusting arrangement forvarying the rate of such counterbalance springs.

One object of the invention is to provide a counterbalance arrangementfor overhead doors having an improved adaptability to doors of differentweights and different displacements between open and closed position.

Another object is to provide in an overhead door a simplified andeffective arrangement for enabling the rate of a counterbalance springto be conveniently adjusted over a wide range, thereby enabling a singlesize of spring to be used effectively in doors of various weights andsizes.

Another object is to provide in an overhead door an adjustablecounterbalance spring arrangement whichis rugged in construction,economical to manufacture, readily adapted to installation in doors nowavailable, and capable of operating effectively for long periods withoutattention.

Other objects will be in part obvious, and in part pointed out more indetail hereinafter.

The invention accordingly consists in the features of construction,combination of elements and arrangement of parts which will beexemplified in the construction hereafter set forth and the scope of theapplication of which will be indicated in the appended claims.

In the drawings:

Figure 1 is a fragmentary side elevational view of an overhead doorassembly incorporating an adjustable counterbalance spring constructedin accordance with the present invention;

Figure 2 is a fragmentary view of a portion of the structure shown inFigure 1, taken on line 2-2 thereof and partly broken away to showcertain structural details;

Figure 3 is an enlarged detail partly sectionalized view of a springadjuster constructed in accordance with the invention;

Figure 4 is an enlarged end view of the structure of Figure 3; and

Figure 5 is a perspective view of certain of the elements of thestructure of Figure 3.

Referring to the drawings, the numeral designates a portion of the frameof a doorway fitted with an overhead door. The numeral 12 designates thedoor, which is articulate and includes a number of hingedly connectedsections 14. The overhead door mechanism includes a frame consisting ateach side of the doorway of a horizontal member 16 and a vertical member18 which in the embodiment shown are angle irons. Supported from theframe at opposite sides of the doorway are the usual tracks 20 withinwhich the door is guided by rollers 22, when moving between its open andclosed positions.

Secured to the horizontal frame members 16 at opposite sides of theframe are supports or bearing plates 28, mounting ball bearings 32within which are journaled ited States the opposite ends of a driveshaft 34. On each end of the drive shaft is pinned a sheave or drum 36on which is wound a flexible strap 38 connected at its free end 40 tothe bottom of the door.

The door is counterbalanced by a torsion spring 42 surrounding the shaft34 and arranged to rotate the shaft in the proper direction to wind upthe straps 38 on the sheaves 36 and thus exert an upward force on thedoor. The spring is relatively long and heavy, preferably of the typehaving abutting convolutions, and is somewhat larger in inside diameterwhen unstressed than shaft 34, as best shown in Figure 3. One end of thespring is maintained stationary relative to the adjacent support 30 andthe other end is connected to the shaft 34 at an intermediate pointthereon. While the spring may be anchored relative to the support 30 inany desired manner, the arrangement shown in the drawing is preferred.This arrangement is shown in detail in Patent No. 2,630,- 597 andincludes a spider 5t) rotatably mounted on the support 35 in coaxialrelation with the shaft 34. The spider 50 includes angularly spacedaxially extending ears 52 and a central body to which is secured anaxially extending tapered anchor tube 54 concentric with the shaft 34.The end of the anchor tube 54 adjacent the spider 50 is larger indiameter than the inside diameter of the spring 52 in its unstressedcondition, while the opposite end of the anchor tube is smaller indiameter than the spring and extends into wedging relation with thespring as best shown in Figure 2. One end of the spring 42 is thuscarried by the anchor tube 54 and frictionally engages the tube in themanner of a spring clutch to prevent relative rotation between theanchor tube and spring when the spring is loaded in a direction such asto wind it up. For the purpose of enabling the spring to be wound up soas to exert any desired degree of counterbalancing force on the door,the earsof the spider are apertured at 56 to permit the insertion of abar or lever to enable the spider to be rotated relative to the support30. When the spring is thus sufficiently wound, the spider may be lockedor fixed against rotation relative to the support 30 by any convenientmeans such as a pin, dog or the like, not shown.

in accordance with the invention, the shaft carries a radiallyprojecting pin 58 which is engaged by a hook 68 on the other end of thespring to support the spring against axial movement and provide adriving connection between the shaft and the spring. The shaft alsocarries a cylindrical sleeve 62, which has an outside diametersubstantially equal to the inside diameter of the spring 42, and isadapted to be inserted concen trically between the shaft and the endportion of the spring 42 adjacent the pin 58. The sleeve has an axiallyextending slot 64 through which the pin 58 extends so as to provide adriving connection between shaft 34 and the sleeve while permitting thesleeve to be axially adjusted along the shaft. The sleeve is formed ofrelatively thin stock and has a plurality of longitudinal groovesforming inwardly extending ribs 66 which enhance the rigidity andincrease the effective thickness of the sleeve. The ribs 66 ride on theshaft and hold the sleeve in concentric relation therewith whileenabling the sleeve to be axially adjusted with reduced friction; A tieplate 68 welded across the slot 64 at one end of the sleeve furtherincreases its rigidity and is threaded to serve as a nut for a setscrew70 by which the sleeve may be secured on the shaft in any selected axialposition.

With this arrangement, since the effective thickness of the sleeve 62 issuch as to substantially fill the space between the spring 42 and theshaft 34, insertion of the sleeve in the spring renders inactive eachsucceeding coil of the spring penetrated by the sleeve. Thus the numberof active coils of the spring and hence the effective length and rate ofthe spring can be readily adjusted simply by axially adjusting thesleeve. To make the adjustment, the spider 50 is first unlocked from thesupport 30 and the spring 42 unwound. The setscrew 7%) is then loosenedand the sleeve slid along the shaft until inserted in the spring to thedesired extent. Engagement of hook 60 with pin 58 prevents axialmovement of the spring during adjustment of the sleeve. Setscrew '70 isthen tightened, the spring is wound up again by rotation of spider 50,and the spider is locked to support 30 to prevent the spring fromunwinding. Winding up of the spring wraps the coils of the springpenetrated by sleeve 62 tightly around the sleeve, thus rendering thosecoils inactive as well as providing a good frictional driving connectionbetween the spring and sleeve.

Thus the effective length and rate of the torsion spring may be readilyadjusted to any desired value simply by inserting the sleeve 62 anyselected amount within the end of the spring. Since the rate of aspring, of course, is a measure of the force it exerts per unit ofdisplacement, by varying its rate a particular spring can be adjusted tosupply the desired amount of counterbalancing force for doors of variousweights and various displacements between open and closed position. Thusit will be appreciated that the present invention greatly increases theapplicability of a single size of spring to doors of various weights andvarious heights of travel between closed and open position. This makespossible a substantial reduction in the number of sizes of springsrequired to be stocked, while permitting easy and convenient adjustmentof an overhead door at the point of installation to provide any desiredtype of operation. The spring adjuster is simple and rugged inconstruction, and is thus economical to manufacture while being capableof operating indefinitely Without attention after being installed.

As many changes could be made in the above construction and manyapparently widely different embodiments of this invention could be madewithout departing from the scope thereof, it is intended that all mattercontained in the above description or shown in the accompanying drawingsshall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the language used in the followingclaims is intended to cover all of the generic and specific features ofthe invention herein de scribed and all statements of the scope of theinvention which, as a matter of language, might be said to falltherebetween.

I claim:

1. In an overhead door having a support, a rotatable shaft journaled inthe support, a spring anchor connected to the support, and a torsioncounterbalance spring surrounding the shaft and connected at one end tothe spring anchor, means for adjusting the rate of the spring comprisinga projecting pin on the shaft about which the other end of the spring ishooked, an axially adjustable cylindrical sleeve on the shaft having oneend extending a selected amount within said other end of the spring,said sleeve having an outside diameter substantially equal to the insidediameter of the spring in an unstressed condition and having an axialslot accommodating said pin, angularlyspaced longitudinal ribs on theinside surface of the sleeve slidably contacting said shaft, and meansfor securing said sleeve in selected axial position on the shaftincluding a setscrew carried by the sleeve and engageable with theshaft.

2. In an over head door mechanism having a support, a rotatable shaftjournaled in the support, a torsion counterbalance spring surroundingthe shaft and connected at one end to the support, and a connectorsecuring the other end of the spring to the shaft, means for adjustingthe rate of the spring comprising an axially adjustable sleeve slidablymounted on the shaft and having one end thereof extending a selectedamount within said other end of the spring, said sleeve being axiallymovable relative to said spring and said connector when said spring isin an unstressed condition.

3. In an overhead door mechanism having a support, rotatable shaftjournaled in the support, a spring anchor connected to the support, atorsion counter-balance spring surrounding the shaft and connected atone end to the spring anchor, and a connector securing the other end ofti e spring to the shaft, means for adjusting the rate of the springcomprising an axially adjustable sleeve slidably mounted on the shaftand having one end extending a selected amount within said other end ofthe spring, said sleeve being axially movable relative to said springand said connector when said spring is in an unstressed condition, saidsleeve having an axially extending opening accommodating said connector,and means for securing said sleeve in selected axial position on theshaft.

4. Spring adjusting means for the torsion couuterbal ance spring of anarticulate overhead door of the type having a support, a rotatable shaftcarried by the support and surrounded by the torsion spring, a springanchor connected to the support and to one end of the torsion spring,and a connector securing the other end of the spring to the shaft, saidadjusting means including an axially justable sleeve slidably mounted onthe shaft and having one end extending a selected amount within saidother end of the spring, said sleeve being axially movable relative tosaid spring and said connector when said spring is in an unstressedcondition, and means on the other end of the sleeve for securing saidsleeve in selected axial position on the shaft.

5. Spring adjusting means for the torsion counterbalance spring of anarticulate overhead door of the type having a support, a rotatable shaftcarried by the support and surrounded by the torsion spring, a springanchor con nected to the support and to one end of the torsion spring,and a connecting pin securing the other end of the spring to the shaft,said adjusting means including an axially adjustable sleeve slida'blymounted on the shaft and having one end extending outwardly from saidother end of the spring and the other end of said sleeve extendingwithin the spring, said sleeve being axially movable relative to saidspring and said connecting pin when said spring in an unstressedcondition, said sleeve having an axial slot to accommodate saidconnecting pin, and means on its sleeve outwardly of the spring forsecuring said sleeve in selected axially adjusted position.

References Cited in the file of this patent UNITED STATES PATENTS

